1. Field of the Invention
This invention relates to measurement of viscosity. More specifically, the invention is a parallel plate system that collects data that can be used to determine viscosity.
2. Description of the Related Art
The classic principle of viscosity envisions that a liquid or viscous material under test is uniformly sheared between two parallel plates with the resulting resistance to the shear being measured in the direction of shearing. Using this ideal set-up, the amount and rate of shear will be uniform over the full volume of the material under test. However, this classic and ideal arrangement is not practiced by most commercially-available instruments. Rather, commercial viscometers (i.e., used for low viscosity materials) and rheometers (i.e., used for higher viscosity materials) typically dispose a material under test between rotating disks or cylinders, and then measure the resistance to rotation in order to determine viscosity. However, the shear forces measured by these apparatus will vary with radius. Accordingly, the viscosity determinations made with these shear force measurements are not an absolute viscosity.